Various bicycle frames are known from the prior art for two-wheeled vehicles, such as bicycles. Two-wheeled vehicle frames can be fabricated, for example, by means of the conventional tubular construction made of steel. In this process, various round tubes are joined together at their ends in order to form, for example, part of a two-wheeled vehicle frame, such as the main frame. By main frame is meant, in the context of the two-wheeled vehicle frame, especially the central frame piece with no further add-on features, such as a rear section. However, design freedom is restricted in this construction in the design of the two-wheeled vehicle frame. Accordingly, the material steel has been almost entirely supplanted in the manufacture of such frame units by other materials, such as aluminum or carbon fiber-reinforced materials.
Thus, for example, WO 2013/029788 A1 discloses a two-wheeled vehicle frame formed by half-shells which are made of a fiber-reinforced thermoplastic material.
US 2015/0048592 A1 also specifies that materials such as aluminum, carbon fibers, or titanium are used rather than steel. But with new materials, defects such as cracks may occur when welding the frame together. The use of a left and a right frame body is proposed. Furthermore, it is proposed to employ reinforcing sheets.
US 2009/0212530 A1 likewise specifies that the conventionally used steel tubes are a disadvantage and that materials such as aluminum, magnesium, titanium and fiber-reinforced plastics are more advantageous. It is disclosed that the frame of a bicycle is made from a left and a right half-shell.
The use of carbon fibers or aluminum, however, results in relatively poor recycling properties of the frame. Furthermore, the use of reinforcing sheets results in more costly fabrication methods.
DE 10 2012 004 174 A1 describes frame components of a two-wheeled vehicle system. A single frame component can be produced from a first and a second half-shell made of molded sheet metal parts. In order to form the main frame, however, further frame components are needed, which accordingly makes the fabrication costly.
Thus a need exists for frame units and methods of manufacturing frame units that offer a high degree of design freedom and avoid the drawbacks of the prior art.